<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <button id="btn">button</button>
    <script>
      (function () {
        function Button() {
          this.oBtn = document.getElementById("btn");
        }

        Button.prototype = {
          init() {
            this.bindEvent();
          },
          bindEvent() {
            this.oBtn.addEventListener("click", (e) => this.btnClick(e), false);
          },
          btnClick(e) {
            console.log(e);
            console.log(this);
          },
        };
        new Button().init();
      })();
    </script>
  </body>
</html>
